The present invention is drawn to a method and apparatus for treating a gas sample containing sulfur and, more particularly, a method and apparatus for treating a gas sample containing sulfur so as to prohibit the degradation of the sulfur content of the gas sample over time when stored.
One of the major concerns facing industry today is the control of environmental pollution. One of the most harmful pollutants present in process gases used and/or produced by industry are sulfur compounds. The undesirability of sulfur compounds are exhibited not only in environmental pollution caused by burning of gas containing sulfur but also corrosion of plant and laboratory equipment which results from contact with sulfur compounds.
In light of the foregoing, it is highly desirable to be able to accurately analyze process gases and the like and their sulfur content in order to insure proper treatment of said gases so as to avoid the deleterious effects attributed to the sulfur in such process gases. To date, the sampling and storing of sulfur gases has remained an unsolved problem. The main reason for this is that the sulfur content of a gas sample which is being analyzed tends to degradate over time and, therefore, the value measured tends to be lower than the true value of the sulfur content of the gas actually being employed in various commercial situations. This decomposition of sulfur has been observed even at sulfur concentrations below 5% and occur in all types of gases whether they be natural gases, process gases or air.
The prior art has attempted to address the foregoing problem. "Methods of Sampling and Storage of Air containing Vapors and Gases", Int. J. Air. Poll., Vol. 2, pp. 142-158, 1959, quantifies several of the difficulties encountered in the storage of sulfur compounds including the difficulty of measuring concentrations of sulfur compounds as compared to various other compounds, and the fast decomposition time of the sulfur compounds over time. While it was found that the decomposition time of sulfur dioxide could be extended by proper choice of storage container, decomposition nevertheless occurs over a rather short period of time. Thus even with a proper choice of materials, effective long-term storage is not possible.
In addition to the difficulties of storing sulfur compounds, it is likewise difficult to accurately measure the concentration of sulfur compounds in gases. One of the most reliable alternatives available to date for the quantitative determination of sulfur content is the Drager method. Although the Drager method allows measurements to be made in the field, the method has several limitations: reduced accuracy, the method is sensitive to only some sulfur species, it requires a great deal of expertise by the operator, and optical interference appears whenever more than one sulfur compound is present. Further, the Drager method provides no means for storage of the gas samples.
Other techniques have also been developed for the analysis of sulfur compounds.
Kimbell, U.S. Pat. No. 3,756,781 teaches a method of analyzing sulfur content in hydrocarbons by first breaking the hydrocarbons down into simpler molecular structures.
Sisti, U.S. Pat. No. 4,293,308 discloses a method and apparatus for determining very small percentages of sulfur in gas samples.
Overall, sulfur compounds in gases are very difficult to measure with time due to the breakdown of the compounds while in storage. Yet, as the harmful effects of these compounds appear from even very low concentrations, it is desirable to detect concentrations of sulfur in the parts per billion range. There exists a need for a simple method and apparatus to sample and store gases containing sulfur compounds with little or no breakdown of the compounds while in storage, so that sulfur concentrations can be accurately measured at later times. In addition, to be used more effectively, such an apparatus should be portable so that it may be moved to the supply of gas. There are many applications which require an accurate sulfur reading at later times, and none of the prior art suggests such a solution for this problem.
Accordingly, as aforementioned, it would be highly desirable to provide an efficient method and apparatus for treating sulfur containing gases so as to prohibit the degradation of the sulfur contained in the gases over time thereby allowing for an accurate measurement of the actual sulfur content of the gases.
Accordingly, it is a principal object of the present invention to provide a method and apparatus for storing sulfur containing gases so as to prohibit the degradation of the sulfur content of the gas over time.
It is a particular object of the present invention to provide a method as aforesaid wherein the sulfur containing gas is pretreated prior to storage so as to prohibit degradation of the sulfur content of same over time.
It is a still further object of the present invention to provide a storage container which is non-reactive to sulfur contained in a gas sample.
It is a further object of the present invention to treat a sulfur containing gas so as to prohibit the degradation of same over time by dehydrating the gas and storing the gas in non-reactive containers.
Further objects and advantages of the present invention will appear hereinbelow.